Liquid laundry detergent compositions are available in the form of water-soluble unit dose articles. Such water-soluble unit dose articles are preferred by consumers as they are convenient to use and reduce accidental spillage during detergent dosage in the wash operation.
Such water-soluble unit dose articles comprise a water-soluble film, preferably a polyvinylalcohol containing film that is formed into a pouch comprising an internal compartment. The liquid laundry detergent composition is comprised within the internal compartment such that the liquid laundry detergent composition is surrounded by the film and in contact with the film that forms the inner surface of the internal compartment.
During manufacture, a first film is deformed in a mould to form an open cavity into which the liquid laundry detergent composition is added via a filling nozzle. After filling a second film is laid over the open filled cavity and sealed to the first film about a seal area.
However, an issue is that the liquid laundry detergent composition tends to ‘string’ between the cavity and the filling nozzle. This ‘stringing’ is the phenomenon wherein due to the properties of the liquid it remains attached to the nozzle forming a ‘capillary’ between the nozzle and the open cavity. As the apparatus moves the filled cavity away from the nozzle and brings a new cavity to be filled into position underneath the nozzle, the distance between the nozzle and filled cavity is sufficient to break the ‘string’. However, this results in some of the liquid laundry detergent composition from the string accidentally falling onto other parts of the open unit dose article such as the seal area. This can affect the ability of the two films to be sealed together and can result in premature rupture or failure of the unit dose article.
Therefore, there is a need in the art for a liquid laundry detergent composition suitable for use in a water-soluble unit dose article whereby the instances of stringing of the liquid laundry detergent composition during manufacture of water-soluble unit dose articles comprising said liquid laundry detergent composition are reduced.
It was surprisingly found that the liquid laundry detergent composition of the present invention wherein the presence of 1,2-propanediol and dipropylene glycol in specific ratio to one another and presence of anionic and non-ionic surfactants in specific ratios to one another addressed this technical problem.
It was also further surprisingly found that when formed into a water-soluble unit dose article the plasticization properties of the film as manufactured were minimally affected by contact with the liquid detergent of the present invention over time. Upon manufacture of the film, it has certain dissolution and tensile properties. Careful balance of the film plasticization properties are needed to ensure the film is not too ‘floppy’ hence affecting the unit dose article aesthetics and its dissolution characteristics when contacting water, and not too brittle, leading to unwanted premature rupture of the unit dose article ahead of use. This plasticization of the film can be negatively affected by contact with the liquid detergent over time.
In addition it was also surprisingly found that water-soluble unit dose articles comprising compositions according to the present invention exhibited improved dissolution profiles in water as compared to comparative water-soluble unit dose articles.